Prior to the advent of the instant invention, prosthodontic systems have been extremely labor intensive and time consuming, requiring a considerable amount of skilled labor to custom hand-make each prosthodontic unit for each case. Recent prior art CAD/CAM-CNC systems for manufacturing prosthodontic pieces require new skill sets and higher intellectual levels of skill than older systems, forcing the majority of labs in the USA (1-5 person small labs) to resist adopting advanced materials and methodologies and/or have to outsource such capabilities and subsequently label the result “premium” goods and services. Even through outsourcing, contemporary technological prior art prosthodontic systems are extremely inefficient, making the availability of high quality, cost-effective prosthodontic pieces nonexistent.
Examples of a prior art prosthodontic systems include the Lava™ two-stage zirconium dioxide system offered by 3M ESPE, and the Precident™ one-stage Bio-HIP Y-TZP (High Heat and Isostatic Pressure formed ytrium stabilized tetragonal zirconium polymorph) offered by DCS of Switzerland. The Lava™ System utilizes a zirconia dioxide block that is CNC milled in a greenware state then secondarily heat sintered. The Precident System mills directly from the harder presintered Bio-HIP Y-TZP block.
My prior inventions disclosed in U.S. patent application Ser. Nos. 60/566,855, filed Apr. 30, 2004 and 60/543,038 filed Feb. 6, 2004, the disclosures of which are incorporated herein by reference in their entirety, provide systems for simultaneously manufacturing a custom dental crown coping and ceramic infrastructure (abutment or ceramic portion of the abutment if two piece) to reduce the amount of labor, time and materials. My prior inventions can be used to manufacture pieces from a greenware stage prior to sintering, or alternatively from an already ceramic infiltrated sintered material, such as a Bio-HIP Y-TZP. Notwithstanding, all prior art processes discussed above mill crown and bridge cores/crowns and bridges from a single block of material with a single axis machine. All current systems require that a technician continuously attend the CNC crown and bridge core/crown and bridge machines to load and change blocks after a limited number of units are produced, and to manually separate finished units from the blocks to avoid trial and error “fit” re-identification.
The maximum number of crown core/crown pieces that any system of the prior art can currently make is 8-16 units/day (capable with a DCS machine, which can cut from 2 blocks before requiring shut down and material exchange), which can take in excess of 24 hours and which requires individual separation of the units from blocks by hand. All other machines (other than a DCS machine) require the block/lug to be changed for each crown/crown core, or at least one block change for each 3-4 crown or bridge core/crown and bridge units. For example, Hint-ELs® Zirconium TZP HIP, which comes in a disc (similar to a hockey-puck) shape for cutting bridges and a two-stage cylindrical (similar to a magic marker) shape for individual pieces, can be automatically feed into a milling machine such that multiple pieces can be cut without the requirement that an attendant mechanically remove the completed work and que-up materials from a hopper on the machine. Nevertheless, as each piece is unique, such machines must be shut down for removal of the pieces after they are cut to avoid confusion among multiple pieces. All machines, other than a DCS machine, cut crown core/crowns from a non-sintered greenware stage. In such machines, the exchange of blocks is manual, and time consuming. Although the process is “computer numeric controlled” (CNC—meaning that a human does not have to manually make the piece), the production time and set up is such that the technician has to continuously monitor the machinery or at the least be mindful of the ticking clock and the end of the process. Thus, true automation efficiencies in the work place are difficult, if not impossible to obtain.
All prior art processes recognize the TZP phase of zirconium to be the strongest of the metal-free materials. Unfortunately, all metals have trace elements that may irritate some individuals' soft tissues. Bio-HIP Y-TZP provides a non-metal hypo-allergenic option for manufacturing crown and bridge cores/crowns and bridges; however Bio-HIP Y-TZP is expensive, hard to work with, and so hard it eats diamond burs in the manufacturing process. Therefore, none of the processes of the prior art (whether cutting either non-sintered or sintered material) are efficient enough to make safe non-metal crown cores readily available and/or affordable for all people, and are intended primarily at present for affluent patients.
Using Bio-HIP Y-TZP via CAD/CAM and CNC manufacturing is known to offer the most precision as no variable result post production process is required (i.e. sintering). Notwithstanding, the prior art systems waste too much material (raw material and burs) and take too long, making what is the best material for crown core/crowns expensive. Thus, the use of Bio-HIP Y-TZP through prior art processes is not cost effective enough in production to make the best product available for all patients. Therefore, it would be beneficial to provide a process that increases the efficiency of using materials such as Bio-HIP Y-TZP for individual crown cores/crowns so as to eliminate socio-economic discrimination in dentistry, and level the playing field in price and honesty of materials used.